Business Restructuring Charges - Summary of Restructuring Accrual Activity (Detail) - USD ($) $ in Millions	1 Months Ended	9 Months Ended
	Dec. 31, 2015	Jun. 30, 2016
Restructuring Reserve [Roll Forward]
Balance at September 30, 2015		$ 62
Charged to expense		199
Cash payments		(112)
Non-cash settlements		33
Other adjustments		66
Balance at June 30, 2016		50
Write-off of assets relating to the sale of a business	$ 28
Employee Termination
Restructuring Reserve [Roll Forward]
Balance at September 30, 2015		62
Charged to expense		53
Cash payments		(65)
Non-cash settlements		0
Other adjustments		0
Balance at June 30, 2016		50
Share-based Compensation
Restructuring Reserve [Roll Forward]
Balance at September 30, 2015		0
Charged to expense		33
Cash payments		0
Non-cash settlements		33
Other adjustments		0
Balance at June 30, 2016		0
Other
Restructuring Reserve [Roll Forward]
Balance at September 30, 2015		0
Charged to expense		113
Cash payments		(47)
Non-cash settlements		0
Other adjustments		66
Balance at June 30, 2016		$ 0